This antibody reacts with mouse PD-1 (programmed death-1), a 55kDa member of the Ig superfamily. PD-1 contains the immunoreceptor tyrosine-based inhibitory motif (ITIM) and plays a key role in peripheral tolerance and autoimmune disease in mice. PD-1 is expressed mainly on activated T and B lymphocytes. Two novel B7 Family members have been identified as PD-1 ligands, PD-L1 (B7-H1) and PD-L2 (B7-DC). Evidence reported to date suggests overlapping functions for these ligands and their constitutive expression on some normal tissues and upregulation on activated antigen-presenting cells. Similar to J43, another mAb to mouse PD-1 (Cat. No. 16-9985), RMP1-14 blocks the binding of both B7-H1-Ig and B7-DC-Ig to PD-1 transfectants.